POS0564 THE IMPACT OF BIOSIMILAR SWITCHING POLICIES IN INFLAMMATORY ARTHRITIS ON UPTAKE AND SPENDING IN BRITISH COLUMBIA, CANADA
Authors: A. Mcclean, M. Harrison, L. Cheng, M. Tadrous, F. Clement, N. Bansback, M. Law
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The uptake of biosimilars has been suboptimal in North America. In response, in 2019, British Columbia (BC) became the first jurisdiction in North America to require patients with inflammatory arthritis to switch to a biosimilar version of infliximab and etanercept to maintain public coverage through the 'Biosimilars Initiative' policy. In 2021 this policy was extended to include adalimumab. The Biosimilars Initiative extended a previous policy which required people starting a biologic to use a biosimilar. Large commercial insurers which provide supplementary drug coverage also introduced biosimilars policies in line with the BC provincial government. Under both biosimilar switching policies, exceptional coverage to reference products was allowed if medically needed. <h3>Objectives</h3> To quantify the impact of the Biosimilars Initiative and the initial policy requiring new initiators to a biologic to use a biosimilar on uptake and spending on biosimilar infliximab, etanercept, and adalimumab in British Columbia (BC). <h3>Methods</h3> Administrative claims data in BC from January 2013 through March2023 were analyzed using interrupted time series analysis, a quasi-experimental study design commonly used to evaluate policy changes. Two policy interventions were evaluated: (1) <i>new starts</i>, whereby individuals initiating infliximab, etanercept, or adalimumab for the first time were required to start the biosimilar (implemented between Feb 2016 and July 2017), and (2) <i>mandatory switching</i>, which required those already receiving infliximab or etanercept (implemented between May and Nov 2019), or adalimumab (implemented between April and October 2012) to switch to the biosimilar version in order to maintain coverage. A segmented linear regression was used to model the level and trend change in biosimilar etanercept and infliximab utilization and spending before and after the two policy interventions. <h3>Results</h3> We identified 208,984 BC residents ≥18 years who qualified for public drug coverage, were treated with etanercept or infliximab, and were eligible for analysis between January 2013 and November 2020. After the <i>new start</i> policy, we detected a small gradual increase in the proportion of biosimilar etanercept prescriptions dispensed of 0.65% (95%CI 0.44, 0.85) per month. The monthly trend related to the proportion of total spending on biosimilar etanercept also increased (0.51, 95%CI 0.28, 0.73). After the <i>mandatory switching</i> policy (the Biosimilars Initiative), there was a sustained increase in the proportion of biosimilar etanercept and infliximab prescriptions dispensed of 76.98% (95%CI 75.56, 78.41) and 58.43% (95%CI 52.11, 64.75), respectively. Similarly, there was a persistent increase in spending on biosimilar etanercept and infliximab of 78.22% (95%CI 76.65, 79.79) and 71.23% (95%CI 66.82, 75.65), respectively. Similar results were seen for adalimumab which was switched later. <h3>Conclusion</h3> Our study found <i>new start</i> policies resulted in small, gradual increases in biosimilar utilization. However, the <i>mandatory switch</i> policy, the Biosimilars Initiative, resulted in a marked immediate and sustained impact on uptake. Further analysis will examine changes in other health utilization, and long-term impact on prescribing patterns. These findings may be particularly relevant to areas with a more concentrated insurance system where mandatory switching policies could lead to greater savings. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.